Why Your Low Resting Heart Rate Might Not Be As Healthy As You Think

If you've ever smugly shared your low resting heart rate with your gym partners, you're not alone. A slower pulse is often worn as a badge of peak cardiovascular health in fitness circles. But the relationship between heart rate and health isn't quite so simple.

A new study presented at the European Stroke Organisation Conference questions the traditional narrative, finding that both very low and very high resting heart rates are associated with increased stroke risk. They say the sweet spot for heart rate is actually somewhere in the middle.

Both extremes were bad

Researchers analyzed data approximately 460,000 participants from the UK Biobank for an average of 14 years. During that time, 12,290 strokes occurred. And a clear U-shaped pattern emerged after adjusting for age, sex, and cardiovascular risk factors.

Stroke risk was lowest among people with resting heart rates between 60 and 69 beats per minute. At the extremes, risk climbed. Those with heart rates below 50 bpm had a 25% higher stroke risk, while those at or above 90 bpm faced a 45% higher risk.

This is the largest population-level study to examine this relationship, and challenges the long-standing assumption that lower heart rates are always a sign of good cardiovascular fitness.

The atrial fibrillation caveat

The U-shaped pattern held up even after accounting for established stroke risk factors like hypertension and diabetes. However, the pattern disappeared when researchers looked specifically at people with atrial fibrillation, a condition where the heart's upper chambers beat irregularly, which can allow blood to pool and form clots.

Atrial fibrillation is a powerful risk factor on its own. People with the condition are already five times more likely to have a stroke, so it makes sense that this factor would overshadow the effect of heart rate in the study.

While it may not be helpful in people with atrial fibrillation, this research will provide valuable information for identifying and analyzing stroke risk in the average population. A 2018 review1 confirmed that heart rate is an independent predictor of cardiovascular and cerebrovascular mortality, even after adjusting for other risk factors.

Why extremes may be risky

The researchers also explored potential mechanisms behind these findings, and the explanations differ depending on which extreme you're on.

What this means for you

Resting heart rate is one of the simplest health metrics you can track. The number is easily accessible on most health trackers, but you can also calculate it manually first thing in the morning before getting out of bed. Just hold two fingers to your wrist or neck, count the beats for 30 seconds, and multiply by two.

If your resting heart rate consistently falls outside the 60–69 bpm range, don't panic. It doesn't necessarily mean you're at risk, says Alastair Webb, Ph.D., a co-author on the study, just that a doctor should take a closer look.

"Very low or very high heart rates should act as a signal for clinicians to look more closely at an individual's overall cardiovascular risk and take action to reinforce lifestyle changes and standard prevention strategies," he said in a press release.

If your heart rate sits at either extreme, it's worth mentioning to your doctor at your next visit. They can help determine whether it reflects your fitness level, an underlying condition, or something worth monitoring more closely.

The takeaway

It might sound appealing to have the lowest resting heart rate in your run club or pickleball group, but this research suggests we shouldn't be aiming for extremes. The lowest stroke risk actually falls in the middle, in the 60–69 bpm range.

While more studies are needed to understand whether heart rate plays a direct causal role in stroke, it's a good reminder that this simple metric is worth paying attention to.